1. Field of the Invention
Embodiments of the invention generally relate to an implantable medical device and method for monitoring insulation of an electrode line of the implantable medical device. The implantable medical device includes at least one electrode line having an electrode pole, an electrode feed line, an insulation sleeve and a counter electrode to the electrode line. The insulation sleeve surrounds the electrode feed line and provides insulation between the electrode feed line and an electrolyte formed by bodily fluid.
2. Description of the Related Art
Generally, typical implantable medical devices demonstrate problems with regard to tightness between insulation sleeves of electrode feed lines, for example due to damage of the insulation sleeve or due to openings and gaps in joints between different insulation sleeve portions. Such insulation faults, typically, may, inter alia, produce falsifications of cardiological signals recorded by the electrode line, for example in the case of a cardiac pacemaker, wherein the function of the cardiac pacemaker may be impaired.
Known devices and methods for electrode fault detection are generally implemented to measure and evaluate different parameters, such as electrode impedances, signal amplitudes, interfering signal detection, stimulus thresholds, frequency analyses, various plausibility tests, etc. For example, United States Patent Publication 2011/0160808 to Lyden et al., entitled “Implantable Medical Device Including Isolation Test Circuit”, appears to disclose an electrode fault detection system based on an impedance measurement. According to Lyden et al. , as an alternative verification method to using impedance measurement, a current pulse may be fed between two electrodes and a response signal resulting therefrom, such as a voltage occurring between electrode lines, may be measured.
Generally, known devices and methods for electrode fault detection often demonstrate insufficient sensitivity and specificity. Typically, using an impedance measurement test may not sufficiently and reliably determine insulation faults, since the impedance of the actual electrode poles lies far below the impedance of an insulation fault, and therefore the insulation fault only causes an insignificant impedance drop in the impedance measurement test.
Reliable detection of an insulation fault at an implanted electrode line is therefore of great importance for the functional capability of such an implantable medical device, thus there is a need for an implantable medical device and method for monitoring the insulation of an electrode line of such a medical device.